1. Field of the Invention
The present invention relates to an ionic conductive polymer gel for secondary battery, and also to a lithium-ion battery comprising the ionic conductive polymer gel.
2. Discussion of Background
Conventionally, electrolytic solutions are employed in secondary batteries. However, the use of such an electrolytic solution in a secondary battery has caused various problems, such as the leakage from a secondary battery and the drying of the electrolytic solution in the battery due to the evaporation of the electrolytic solution while in use.
In order to solve these problems, the use of a solid electrolyte has been studied. However, a solid polymer electrolyte comprising an electrolyte salt is a complete solid and therefore has low ionic conductivity and cannot always be used in practice.
In order to increase the ionic conductivity of such a polymeric solid electrolyte, it has been proposed to use, for example, siloxane as a polymeric solid electrolyte as disclosed in U.S. Pat. No. 5,112,512 and phosphazene as disclosed in U.S. Pat. No. 4,849,856.
However, the ionic conductivities of these polymeric ionic conductivities are still insufficient for use in practice in secondary batteries.
Recently, there have been proposed ionic conductive polymer gels, which comprise a polymer matrix, which may be a thermoplastic polymer matrix or a cross-linked polymer matrix, a solvent and an electrolyte salt. These ionic conductive polymer gels, however, cannot satisfy the requirements that they have both high physical strength and high ionic conductivity for use in secondary battery, at the same time.